Re: [PATCH v2 17/20] mm: free_area_init: allow defining max_zone_pfn in descending order

[Vineet Gupta <Vineet.Gupta1@xxxxxxxxxxxx>]

On 5/5/20 2:19 AM, Mike Rapoport wrote:
> From the code I've got the impression that it is either one of them. I.e
> the physical memory is either at
>
> 0x8000_0000 - <end of DDR 0 bank>
> 0x0000_0000 - <end of DDR 1 bank>
>
> or
>
> 0x0_8000_0000 - <end of DDR 0 bank>
> 0x1_0000_0000 - <end of DDR 1 bank>
>
> Is this possible to have a system with three live ranges? Like
>
> 0x0_0000_0000 - <end of DDR 1 bank>
> 0x0_8000_0000 - <end of DDR 0 bank>
> 0x1_0000_0000 - <end of DDR 2 bank>

We don't have such a system, but it is indeed possible in theory. The question is
 - Can other arches have such a setup too
 - Is it not better to have the core retain the flexibility just in case

Thx,
-Vineet